Telephonic and telegraphic repeater or relay



' 1,645,987 Oct. 18, 1927' A, v. T. DAY

TELEPHONIC AND TELEGRAPHIC REPBATER on RELAY Original Filed July 8, 1915 5 Sheets-Sheet 1 Fly A. V. T. DAY

Oct. 18, 1927.

TELEPHONIC AND TELEGRAPHIC REPEATER OR RELAY s Sheets-Sheet 2 Original Filed July 8, 1915 Wain/3625'.

. 1,645,987 0 1927' A. v. T. DAY

TELEPHONIC AND TELEGHAPHIC REPEATER OR RELAY Original Filed July 8, 1915 5 sheets-sheet W 625 FQQJXS, 22 126726 01 ALBERT V. T. DAY,

, 1645.987 PATENT OFFICE.

01 PARIS, FBAIICE.

TELEPHON IC AND TELEGRAPHIC REPEATEB OR RELAY.

Application filed July 8, 1915, Serial My invention relates to relays or repeaters for telephonic transmission, or for telegraphic transmission involving currents of harmonic or telephonic character.

The object of my invention is to provide two-way repeating apparatus which will avoid the reflex of a current wave or impulse from the circuit or transmission section wherein it is repeated back into the circuit or section from which it was received, but without incurring that impairment of efiiciency and limitation of service involved in the usual circuit-balancing or reflexioncompensating methods which not onl reatly reduce the power-modulus or mo u us of amplification'but also require special adjustment for all conditions and for all substantial changes in their reciprocal circuits or transmission sections, which latter requirement makes it impracticable either to interpose ia eaters immediately between telephone subscribers circuits and the termini of long transmission lines, or to employ telephone repeaters generally in indiscriminate service.

Repeaters operated in accordance with my invention may develop substantially the full power-modulus of one-way transmission without balancing or compensating losses, and may be employed at all points where it is desirable to amplify-thetransmitted current and without regard for the properties or variations in the reciprocal transmission circuits. Hence, in the adaptation of my invention to long-distance telephony, re eaters may be placed at the exchange en s of two subscribers circuits communicating through a long transmission line, or may be connected at the longdistance switchboards nearest to the respective subscribers, so that each repeater, when transmitting to the long transmission line, will be actuated by substantially the full power of the speaking subscribers transmitter, andwill conse quently deliver to the long line an amplified telephonic power greatly exceedingthe subscribers transmitter power.

Therefore in this practice, the avera e telephonic power of the ordinar transmitter may be adopted as the minimum limit of power attenuation in long-distance transmission, and repeaters may be inserted arbitrarily at such intervals as may be necessary to maintain this standard, and without regard for the characteristics of the reci rocal sections of the transmission line. us,

110. 576,846. Renewed m 21, 1922.

in lieu of employing such delicate repeaters as are necessary to amplify a telephonic current of subnormal power in accordance with the present practice, my invention permits the employment of repeaters under conditions insuring the actuation of each repeater by a current of full normal transmitter power, wherefore the repeaters may be made more rugged; andalso in dealing with much larger telephonic powers the relative effects of their material imperfections and the consequent distortion, will be much reduced. Also, in the adoption of av much higher power-standard for long-distance transmission, the relative value of foreign induction noises will be proportionately reduced, and a line which would otherwise be too noisy for service can be rendered practically silent by maintaining therein a telephonic ower of abnormal intensity which, if desire may be reduced by resistance to normal value in delivery to the subscribers line, while the foreign currents will concurrently be reduced to values inaudible or sufiiciently faint.

In virtue of its indifference to circuit properties and their relations and changes,

my repeater may be widely employed -for efficient long-distance transmission through any succession of arbitrarily connected inferior circuits of short-distance standard which, under the present regime, are useless for such service. Thus a great net-work of lines of medium standard now covering the continent can be made available for longdistance traffic in all directions between innumerable points which, under the present practice, could only acquire telephonic communication through a prohibitively expensive installation of innumerable special lines of high-grade long-distance standard.

Since my invention in its broadest aspect consists in means for co-ordinating repeaters of any species in two-way trafiic between reciprocal circuits or consecutive transmission sections, it appears that it can still contribute its advantages to the individual eificiency of any type of repeater which may hereafter be devised, however superior as a repeater per se, excepting only a type of repeater which might dispense with the need which has heretofore been common to all types.

'In short, it will be apparent to experts that in its manifest relation to the present known state of the art, my invention is capable of vastly extending the commercial sco and utility of long-distance telephony, wit out additional investment in equipment, except the comparatively nominal cost of the necessary repeaters.

The seven figures of the accompanying drawings are diagrams of difierent embodiments of my invention.

In Figure 1, a and b are the reciprocal circuits or transmission lines between which the repeater is interposed, and 2 and 2 are the repeater-actuating coils respectively energized by these lines. These coils operate vibratory devices or armatures 3 and 3" respectively, which respectively control the local primary microphone circuits 4 and 4* to deliver amplified current to the reciprocal circuits b and a/respectively. Each vibratory armature co-acts with a pair of pendant contact balls, 5 or 5" normally making light contact with its opposite sides and thus conductively communicating with each other when the armature is passive. The halls are suspended by light conductive cords, and each repeater-actuating coil is bridged across its energizing line in series with that pair of cords and contact balls which co-act with the vibratory armature of the reciprocal coil. The contact balls and co-acting intervening portions of the vibratory armatures are preferably of polished metal. The balls have such a relatively long pendulum period and such a slight angle of suspension as to insure that any phonetic vibration of either armature suflicient to effectually operate its microphone, will efiectually prevent its coacting balls from making .simultaneouscontact with it, thereby opening the connection between these balls and thus opening that circuit-branch which connects the reciprocal repeater-actuating coil in its circuit.

The condensers 6 and 6 prevent the flow of any continuous-current components through the repeater-actuating coils, If such a current were flowing through either coil at the instant of its disconnection by the phonetic operation of the reciprocal coil, the coil thus cut out of circuit would react to the current change thus induced within it to vibrate its own armature and in turn out out the phonetically operating reciprocal coil which should remain in control of the transmission.

In Figure 2, the repeater-actuating coils 2 and 2" are normally bridged across their respective lines in series respectively with the magnet-controlled switch-contacts 13 14* and 13", 14, which are normally held closed by' the electro-magnets 10 and 10, respectively. The line-energizing secondaries of the transformers 17 a and 17", which transmit respectively to the lines I) and a, are held normally open at the magnet-controlled switch-contacts 13, 15 and 13 15", respectively, but are bridged across their respective lines when these contacts are respectively closed. \Vhile the magnets 10 and 10 are energized, they respectively hold open the switch-contacts 12, 16 and 12", 16 included respectively in the local or primary microphone circuits 4 and 4", thus reducing the current consumption and microphone heating.

Under the foregoing conditions, which obtain while both lines are passive, the communication between the lines is severed, and one-way communication is automatically established in the required direction by the initial phonetic activity of either line.

For instance, if the repeater-actuating coil 2 vibrates its armature, the microphone of the primary circuit 4 is actuated, as well as the pair of pendant balls 5, 5"", which contact withthe armature to functionate as microphone electrodes in series respectively with the opposite coils 7, 7 which jointly vibrate their intervening armature co-acting in turn with the pendant contact-balls 9 9*, to open the circuit of the magnet 10 in a manner already explained with respect to the contact balls 5 of Figure 1. Obviously the secondary or subordinate agitator 7 7 may greatly augment the ballistic power of the coil 2* so that even a very minute or inaudible current in that coil will indirectly vibrate the balls 9 with considerable force and thus effect the positive deenergization of the magnet 10; thereby closing the microphone circuit 4 at the contacts 12, 16"; and concurrently opening the contacts 13, 14 to disconnect the reciprocal coil 2*; and concurrently closing the contacts 13, 15 to connect the secondary of the transformer 17 in the receiving line b.

The entiremechanical movement of the magnet armature l3 may be very minute, probably much less than one tenth of a millimeter. If the effectual breaking of the local microphone circuit 4 requires a movement of the armature 12 too Wide to permit sufliciently instantaneous reclosure, this control may be omitted and the microphone circuit may be left continually closed while the repeater is in service. Hence, the entire operation of establishing the connections for the required one-way'transmission, in response to the initial phonetic activity of either line, may consume only a negligible time, so that only an inappreciable part of the initial phonetic current Will be lost in the interim.

Obviously the intermediate agitator 7 7 a could be omitted and the magnet 10 could be controlled directly by the contact balls 5 5. Obviously also, this intermediate agitator could be employed in the scheme of Figure 1, its contact balls 9 being placed in series with the proper repeater-actuating coil, in lieu of the contact balls 5" of that figure.

In Figure 3, as in Figure 1, the connection of each repeater actuating coil, 2* or vibration of the armature of the reciprocal coil. For instance the contact balls 19, 19" which normally have conductive connection through the intervening insulated end 20 of the armature of the coil 2, are caused by the phonetic energization of that coil to break this connection and thus disconnect the reciprocal coil 2 from the line b. In this instance the contact balls are mounted on balanced pivoted arms, and their contact pressure and natural period of. oscillation are determined by light torque springs such as 21. I

In this instance each vibrating armature carries also another insulated piece such as 23 coacting with another pair of. balanced ballistic circuit-breakers such as 22, 22*, to disconnect from the repeater-actuating line the secondary of the reverse-direction transformer such as 24 which is not in service. Thereby is avoided the waste of repeateractuating current in this idle secondary. These transformer-disconnecting circuitbreakersalsoassist in two ways to prevent interference between the reciprocal repeating devices. Manifestly when the circuit a transmits to the circuitb the opening of the secondary of 24 would prevent any reflex of transmission from b to u even if the coil 2 were slightly excited by the line b owing r to its imperfect disconnection by the breaker 19, 19. Also, if the coil 2 is slightly e2 cited by initiation of the first telephonic wave in the transmission from a to b before the breaker '19, 19" is effectually opened, the resulting tendency to produce a movement of the armature of 2 will be self-curbing in consequence of opening the circuit-breaker controlling the secondary of 24 from which the coil 2" is excited, thereby suppressing or limiting the undesired movement of this armature while the armature of 2 moves sufliciently to eflectually disconnect and quiet the coil 2". If the coil 2 does in fact produce such a slight suppressed movement of its armature before this coil is efl'ectually disconnected by the breaker 19, 19, then in order that this self-suppressed movement shall not react to disconnect the repeateractuating coil 2 from its line, the ballistic circuit-breaker which controls this connection may be made slightly less sensitive than the breaker operated by 'this suppressed movement of the armature of 2 to disconnect 24 from theline 1). Thus the selfsuppresed armature movement which disconnects 24 will not disconnect 2. As soon as the coil 2 is efi'ectually disconnected by the breaker 19, 19, its suppression of trans mission from 24, to b ceases, and transmission from a to b is fully established. If

this initial suppression occurs at all, it will be nugatory in its short duration.

In Figure 4 the balanced ballistic circuitbreakers are operated by the respective repeater-actuating' coils to respectively open the normally closed local circuits of magnets 25*and 25 which jointly control a common armature 26 adapted to close alternative con- -tacts 27" or 27, thus alternatively connecting the secondaries of the transformers 24 or 24* in their respective lines for transmis sion in alternate directions. For example, when the line a becomes active it de-energizes the magnet 25* which thereupon permits the magnet 25 to preponderate and attract the armature to close the contacts 27 and connect the transformer 24 lwl' trans mission from a to b. This operation is virtually instantaneous so that there is no appreciable abbreviation in the transmission, and in any eventthis instantaneous hiatus occurs not at the beginning of each sound but only at the beginning of each reversal of transmission. After transmission is started in one direction, for instance as just noted, the armature 26 remains set for that direction of transmission during all pauses in telephonic activity. and until reverse transmis sion is started, which reverses the position of that armature to remain likewise set for the reverse transmission.

Since both repeater-actuating coils 2 and 2' are continually connected in their respective lines, it is apparent that-after the phonetlc activity of the coil 2 has set the switcharmature 26 for transmission from a to b, the resulting activity of the coil 2 must open the circuit of the magnet 25, so that both magnets controlling the armature 26 Wlll be de-energized. It is a mere matter of design'to provide that the armature shall stick with sufiicient firmness in the position it occupies when the second magnet is deenergized. It may be polarized so it will develop a bias toward the nearer magnet core, or its contact members may be of polarized steel so they will tend to stick together. a

In Figure 5, the control of the directionreversing armature-switch 26 is effected as inFigure4, except that the ballistic circuitbreakers are operated by armatures 32 and 32 vibratedby magnets 31' and 31 serving this pu ose exclusively and which may be energize by the lines a and b respectively.

The adiustable resistances 30 and 30 may serve to damp the responsiveness of the ballistic circuit-breakers to foreign currents weaker than the phonetic currents which the repeater is intended to transmit, or the sensitiveness of the circuit-breakers to such foreign currents may be reduced by increasing the contact-sustaining efforts of their torque springs such as before mentioned. It must be noted that this diflerentiation 0f responsiveness to foreign and telephonic currents is entirely practicable when the telephonic transmission power is not permitted to drop at any point in transmission much below the normal power of a subscribers transmitter 'working through a short-distance circuit, or in any event when the proportionate strength of the foreign currents is reduced as much as usual by balanced line construction. If the repeater-actuating current is permitted to drop to a much attenuated subnormal value. then in order to insure positive actuation of the ballistic switches, each armature 32 and 32 may control one or more intermediate agitators to operate these ballistic devices as in Figure 2. The adjustable resistances 29 and 29 may be employed to reduce the incoming tel ephonic power when necessary. For instance, if a were a short-distance circuit lead ng to the subscribers instrument, then the telephonic current coming from b with normal transmitter power, as aforesaid. would be too intense when fully amplified in a, and the resistance 29 would be inserted to reduce the power modulus of the repeater. while at the same time reducing the waste of current in the repeater-actuating coil 2 during the reverse transmission from a to b. In this case the resistance 29 would be. cut out. These resistances 29 and 29 would as well serve their function of reducing the power-modulus if connected immediately in series with the primaries or secondaries of the transformers 24 and 24 respectively. When the incoming or repeater-actimting current is permitted to drop much toward subnormal value, they will not be required.

In Figure 6 the ballistic circuit-breakers 22" and 22", and the armature-switch 26, perform the same functions ascribed to the parts correspondingly designated in Figures 4 and 5; but in Figure 6 an extra ar mature-switch 33 is similarly and simulta neously operated by the opposed magnets 25* and 25 to alternately open the contacts 34 and 34'. In this instance each repeateractuating coil, 2 or 2", is bridged across its line through an extra ballistic circuitbreaker 35", 35 or 35, 35*, respectively, op erated by the reciprocal coil; but during transmission in either direction, the circuitbreaker operated by the coil of the secondary line is short-circuited by the contacts 34 or 34" so that this circuit-breaker cannot open the line connection of the repeater-actuating coil of the primary line. This is merely an extra safe-guard against mutual simultaneous disconnection of both repeater-actuating coils.

In Figure 7 the magnets 25 and 25", and their intervening armature 26, perform the same functions as in Figures 4, 5 and 6, but the local circuits 'of these magnets are opened respectively by relay armatures 36 and 36 controlled by electro-magnets energized in series with the phonetic microphones 4 and 4, for instance by the magnets constituted in the transformers 24 and 24" of these circuits respectively. When either microphone is actuated its mean resistance is substantially increased so as to diminish the mean current in its circuit and electroanagnet, and thus release the relay armature controlled thereby, to open the circuit of the respective transmission-reversing magnet 25 or 25".

Many other adaptations of my invention will be obvious, and still others may be inventively devised.

I claim:

1. A means for controlling the transmission through a repeater comprising a number of circuit-breakers in series arranged to control the transmission, and means responsive to the transmission of current to open each circuit-breaker intermittently and prevent simultaneous closure of the circuit breakers, whereby tomaintain one transmission condition of the repeater during such current transmission.

2. Repeating apparatus comprising a num ber of ballistic contact-electrodes, a co-acting contact surface for each electrode, means responsive to the transmission of current to Vibrate the contact surfaces so that one moves toward its co-acting ballistic electrode while another moves away from its co-acting ballistic electrode, and a circuit arranged to control transmission through the repeating apparatus and leading in series through both ballistic electrode and their coacting contact surfaces.

ALBERT V. T. DAY. 

